I'm with the Celia Hammond Animal Trust in London and we are desperate for homes for our feral cats. Stables and farms tend to be ideal locations, where the cats perform mousing duties in exchange for food and shelter. All cats come neutered, vaccinated etc and we provide relocation pens and advice, as well as after care (if the cats need re-trapping for vet treatment).
If anyone knows stables or farms that might be interested, or could share the request on similar horse or farming-related forums, we would be most grateful.